Would these be any good for making a tonneau or boot cover?

They are the right sort of thing, but you need to check if they can do press studs - presuming that is how you intend to secure the cover. You can get some tools which just require a good hit with a hammer which may actually be easier - just practice a couple of times on scrap material first.

I've fitted Tenax fasteners on my tonneau. Although a bit more pricey they are so much better than the lift the eye ones.

No special tools needed either.

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